class_docstr: Handles loading, partitioning, and preparing audio training data.
docstr: Builds a TensorFlow graph to apply the input distortions.
  
  Creates a graph that loads a WAVE file, decodes it, scales the volume,
  shifts it in time, adds in background noise, calculates a spectrogram, and
  then builds an MFCC fingerprint from that.
  
  This must be called with an active TensorFlow session running, and it
  creates multiple placeholder inputs, and one output:
  
    - wav_filename_placeholder_: Filename of the WAV to load.
    - foreground_volume_placeholder_: How loud the main clip should be.
    - time_shift_padding_placeholder_: Where to pad the clip.
    - time_shift_offset_placeholder_: How much to move the clip in time.
    - background_data_placeholder_: PCM sample data for background noise.
    - background_volume_placeholder_: Loudness of mixed-in background.
    - output_: Output 2D fingerprint of processed audio.
  
  Args:
    model_settings: Information about the current model being trained.
    summaries_dir: Path to save training summary information to.
  
  Raises:
    ValueError: If the preprocessing mode isn't recognized.
    Exception: If the preprocessor wasn't compiled in.
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code: def prepare_processing_graph(self, model_settings, summaries_dir):
      """Builds a TensorFlow graph to apply the input distortions.
  
      Creates a graph that loads a WAVE file, decodes it, scales the volume,
      shifts it in time, adds in background noise, calculates a spectrogram, and
      then builds an MFCC fingerprint from that.
  
      This must be called with an active TensorFlow session running, and it
      creates multiple placeholder inputs, and one output:
  
        - wav_filename_placeholder_: Filename of the WAV to load.
        - foreground_volume_placeholder_: How loud the main clip should be.
        - time_shift_padding_placeholder_: Where to pad the clip.
        - time_shift_offset_placeholder_: How much to move the clip in time.
        - background_data_placeholder_: PCM sample data for background noise.
        - background_volume_placeholder_: Loudness of mixed-in background.
        - output_: Output 2D fingerprint of processed audio.
  
      Args:
        model_settings: Information about the current model being trained.
        summaries_dir: Path to save training summary information to.
  
      Raises:
        ValueError: If the preprocessing mode isn't recognized.
        Exception: If the preprocessor wasn't compiled in.
      """
      with tf.compat.v1.get_default_graph().name_scope("data"):
          desired_samples = model_settings["desired_samples"]
          self.wav_filename_placeholder_ = tf.compat.v1.placeholder(
              tf.string, [], name="wav_filename"
          )
          wav_loader = io_ops.read_file(self.wav_filename_placeholder_)
          wav_decoder = tf.audio.decode_wav(
              wav_loader,
              desired_channels=1,
              desired_samples=desired_samples,
          )
          # Allow the audio sample's volume to be adjusted.
          self.foreground_volume_placeholder_ = (
              tf.compat.v1.placeholder(
                  tf.float32, [], name="foreground_volume"
              )
          )
          scaled_foreground = tf.multiply(
              wav_decoder.audio, self.foreground_volume_placeholder_
          )
          # Shift the sample's start position, and pad any gaps with zeros.
          self.time_shift_padding_placeholder_ = (
              tf.compat.v1.placeholder(
                  tf.int32, [2, 2], name="time_shift_padding"
              )
          )
          self.time_shift_offset_placeholder_ = (
              tf.compat.v1.placeholder(
                  tf.int32, [2], name="time_shift_offset"
              )
          )
          padded_foreground = tf.pad(
              tensor=scaled_foreground,
              paddings=self.time_shift_padding_placeholder_,
              mode="CONSTANT",
          )
          sliced_foreground = tf.slice(
              padded_foreground,
              self.time_shift_offset_placeholder_,
              [desired_samples, -1],
          )
          # Mix in background noise.
          self.background_data_placeholder_ = tf.compat.v1.placeholder(
              tf.float32, [desired_samples, 1], name="background_data"
          )
          self.background_volume_placeholder_ = (
              tf.compat.v1.placeholder(
                  tf.float32, [], name="background_volume"
              )
          )
          background_mul = tf.multiply(
              self.background_data_placeholder_,
              self.background_volume_placeholder_,
          )
          background_add = tf.add(background_mul, sliced_foreground)
          background_clamp = tf.clip_by_value(background_add, -1.0, 1.0)
          # Run the spectrogram and MFCC ops to get a 2D 'fingerprint' of the audio.
          spectrogram = audio_ops.audio_spectrogram(
              background_clamp,
              window_size=model_settings["window_size_samples"],
              stride=model_settings["window_stride_samples"],
              magnitude_squared=True,
          )
          tf.compat.v1.summary.image(
              "spectrogram",
              tf.expand_dims(spectrogram, -1),
              max_outputs=1,
          )
          # The number of buckets in each FFT row in the spectrogram will depend on
          # how many input samples there are in each window. This can be quite
          # large, with a 160 sample window producing 127 buckets for example. We
          # don't need this level of detail for classification, so we often want to
          # shrink them down to produce a smaller result. That's what this section
          # implements. One method is to use average pooling to merge adjacent
          # buckets, but a more sophisticated approach is to apply the MFCC
          # algorithm to shrink the representation.
          if model_settings["preprocess"] == "average":
              self.output_ = tf.nn.pool(
                  input=tf.expand_dims(spectrogram, -1),
                  window_shape=[
                      1,
                      model_settings["average_window_width"],
                  ],
                  strides=[1, model_settings["average_window_width"]],
                  pooling_type="AVG",
                  padding="SAME",
              )
              tf.compat.v1.summary.image(
                  "shrunk_spectrogram", self.output_, max_outputs=1
              )
          elif model_settings["preprocess"] == "mfcc":
              self.output_ = audio_ops.mfcc(
                  spectrogram,
                  wav_decoder.sample_rate,
                  dct_coefficient_count=model_settings[
                      "fingerprint_width"
                  ],
              )
              tf.compat.v1.summary.image(
                  "mfcc",
                  tf.expand_dims(self.output_, -1),
                  max_outputs=1,
              )
          elif model_settings["preprocess"] == "micro":
              if not frontend_op:
                  raise Exception(
                      "Micro frontend op is currently not available when running"
                      " TensorFlow directly from Python, you need to build and run"
                      " through Bazel"
                  )
              sample_rate = model_settings["sample_rate"]
              window_size_ms = (
                  model_settings["window_size_samples"] * 1000
              ) / sample_rate
              window_step_ms = (
                  model_settings["window_stride_samples"] * 1000
              ) / sample_rate
              int16_input = tf.cast(
                  tf.multiply(background_clamp, 32768), tf.int16
              )
              micro_frontend = frontend_op.audio_microfrontend(
                  int16_input,
                  sample_rate=sample_rate,
                  window_size=window_size_ms,
                  window_step=window_step_ms,
                  num_channels=model_settings["fingerprint_width"],
                  out_scale=1,
                  out_type=tf.float32,
              )
              self.output_ = tf.multiply(micro_frontend, (10.0 / 256.0))
              tf.compat.v1.summary.image(
                  "micro",
                  tf.expand_dims(tf.expand_dims(self.output_, -1), 0),
                  max_outputs=1,
              )
          else:
              raise ValueError(
                  'Unknown preprocess mode "%s" (should be "mfcc", '
                  ' "average", or "micro")'
                  % (model_settings["preprocess"])
              )
  
          # Merge all the summaries and write them out to /tmp/retrain_logs (by
          # default)
          self.merged_summaries_ = tf.compat.v1.summary.merge_all(
              scope="data"
          )
          if summaries_dir:
              self.summary_writer_ = tf.compat.v1.summary.FileWriter(
                  summaries_dir + "/data",
                  tf.compat.v1.get_default_graph(),
              )
  
imports: import hashlib
  import math
  import os.path
  import random
  import re
  import sys
  import tarfile
  import numpy
  import urllib
  import tensorflow
  from tensorflow.python.ops import gen_audio_ops
  from tensorflow.python.ops import io_ops
  from tensorflow.python.platform import gfile
  from tensorflow.python.util import compat
label_desc: Use image node_id 5 for calling the AudioProcessor obj's underlying member method code with example usage: obj.prepare_processing_graph(model_settings, summaries_dir) without return types